Present multi-axis accelerometer equipment exhibits bias performance of 0.2 milli "g" to 2.0 milli "g". Such equipment which uses piezoelectric bender beam transducers have inherently high electrical impedance and communicate from the rotor to the signal processor via sliprings. The sliprings limit the performance, useful instrument life and reliability, therefore reducing the product use to short time missions such as tactical missiles.
Prior art accelerometers consist of a proof mass with either a mechanical or electrical restoring spring and a means for measuring the deflected angle or the electrical restoring current. A hybrid accelerometer has been developed in which piezoelectric beams are caused to rotate about an axis. An acceleration input causes the beams to deflect, and the deflection is measured through electrical impedance. Changes in impedance are caused by the piezoelectric effect of the bending moments on the beam. It has always been necessary, however, to include the unreliable slip ring contacts for electrical communication.
It is an object of the invention to provide a low cost, compact and accurate system for measuring acceleration. Ideally, such acceleration information must be accurate enough to be used over extended ranges and extended time periods.